Three numbers A, B and C are in the ratio 1 : 2 : 3. Their average is 600. If A is increased by 10% and B is decreased by 20%, then to get the average increased by 5%, C will be increased by-

Question: Three numbers A, B and C are in the ratio 1 : 2 : 3. Their average is 600. If A is increased by 10% and B is decreased by 20%, then to get the average increased by 5%, C will be increased by-

Solution:
Let
A= x, B = 2x, C = 3x.
Then,
x + 2x + 3x = 600 × 3
→ 6x = 1800
→ x = 300

So, A =300, B = 600, C = 900.
New value of A = 110% of 300 = 330
New value of B = 80% of 600 = 480
New average = 105% of 600 = 630

∴ New value of C = (630 × 3) - (330 + 480)=1080
→ Increase in value of C = 1080 - 900 = 180 Tk.